Thai police reiterated the motive for a deadly bombing at a shrine in Bangkok in August was revenge for a crackdown on human trafficking

BANGKOK, Sept 28 (Reuters) - Thai police reiterated on Monday the motive for a deadly bombing at a shrine in Bangkok in August was revenge for a crackdown on human trafficking and they again showed wads of cash that would be used as a reward for their investigators.

Fourteen foreigners were among those killed in the attack, the worst incident of its kind in Thai history. It dealt a fresh blow to a tourism industry recovering from the impact of political protests last year.

"We are confident that the main motive for this crime was Thai authorities destroying the human trafficking network," police chief Somyot Pumpanmuang told a news conference.

No group has claimed responsibility for the attack and police have repeatedly said they did not believe militants were involved, ruling out a motive of revenge for the repatriation in July of 109 Muslim Uighur people to China.

The Uighur issue is sensitive for the government and any link between the bomb and the deportation at China's behest could expose it to criticism that its foreign policy led to the blast.

Uighurs, who are mostly Muslim, say they flee China's western Xinjiang region due to persecution. Beijing rejects that.

For the second time in a month, Somyot appeared with three thick blocks of banknotes stacked in front of him and said the 3 million baht ($83,000) was a reward for his investigators.

While ruling out international militants, Somyot said there may be a link between the blast and Thailand's long-running political divisions through an individual hired to help the suspects in the attack.

That person may have been involved in bombings during political turmoil in 2010 and 2014, he said.

"We cannot rule out this motive, that this may be politically driven," he said, giving no further details.

Authorities said on Friday a man they arrested in August - referred to both as Bilal Mohammed and Adem Karadag - had confessed and was the yellow-shirted suspect seen in security footage placing a backpack at the shrine moments before the blast.

A second arrested man used a mobile phone to trigger the bomb, police have said.

Authorities had said previously it was unlikely either of the two were the bomber in what has been an inconsistent police investigation.

Thailand cracked down on the lucrative trade in humans in the region in May, parking an international humanitarian crisis as criminal gangs abandoned boatloads of migrants at sea rather than risk smuggling them through Thailand. ($1 = 36.2600 baht) (Additional reporting by Pairat Temphairojana and Panarat Thepgumpanat; Writing by Simon Webb; Editing by Robert Birsel)